Apparatus and method for pulsed plasma processing of a semiconductor substrate
US6395641B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | May 16, 2001 |
| Grant date | May 28, 2002 |
| Priority date | — |
| Expiry date | May 16, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/3345
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Apparatus and method for an improved etch process. A power source alternates between high and low power cycles to produce and sustain a plasma discharge. Preferably, the high power cycles couple sufficient power into the plasma to produce a high density of ions (≳1011 cm−3) for etching. Preferably, the low power cycles allow electrons to cool off to reduce the average random (thermal) electron velocity in the plasma. Preferably, the low power cycle is limited in duration as necessary to prevent excessive plasma loss to the walls or due to recombination of negative and positive ions. It is an advantage of these and other aspects of the present invention that average electron thermal velocity is reduced, so fewer electrons overcome the plasma sheath and accumulate on substrate or mask layer surfaces. A separate power source alternates between high and low power cycles to accelerate ions toward the substrate being etched. In one embodiment, a strong bias is applied to the substrate in short bursts. Preferably, multiple burst occur during the average transit time for an ion to cross the plasma sheath and reach the substrate surface. Ions are pulsed toward the surface for etc…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.